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Homework Help: Quantum mechanics question on probability amplitude

  1. May 3, 2012 #1
    1. The problem statement, all variables and given/known data

    What physical phenomenon requires us to work with probability amplitudes rather than just
    with probabilities, as in other fields of endeavour?

    2. Relevant equations

    3. The attempt at a solution

    That the probability of an outcome is given by the square of the modulus of the corresponding probability amplitude? But that's not a physical phenomenon?
  2. jcsd
  3. May 4, 2012 #2
    Is probability a physical phenomenon? I don't think so, but maybe.
    Like any statistical distribution you can use the density to e.g. finding the probability of the particle being a point in space:
    Find the probability that the electron has position x = 2 given that:
    [itex] p(x) = |\psi(x)|^2 = 1/x^2[/itex]
    Then you would be wrong to integrate, but simply doing this would solve it:
    [itex] p(x=2) = 1/2^2 = 4[/itex]
    I don't think you can assign much meaning to the [itex]\psi(x)[/itex] alone.
    Hope that helped a little.
  4. May 4, 2012 #3


    User Avatar
    Science Advisor
    Homework Helper

    'Waves superposition' would be an answer.
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